Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.
Neoplastic disease or cancer is a group of diseases in which genetically abnormal cells tend to proliferate in an uncontrolled manner and may metastasise. Nearly all cancers are caused by abnormalities in the genetic material of the transformed cells. These abnormalities may be due to the effects of carcinogens such as tobacco smoke, ionising radiation, chemicals or infectious agents. Other cancer promoting genetic abnormalities may be randomly acquired through errors in DNA replication, or are inherited and are present in all cells from birth.
Current treatment regimes for cancer include one or more of surgery, chemotherapy, radiation therapy, immunotherapy, monoclonal antibody therapy or other methods. The choice of therapy depends upon the location and grade of the tumour and the stage of the disease, as well as the general health of the patient.
The ultimate aim of the aforementioned treatment regimes is the complete removal of the cancer without damage to the rest of the body. Sometimes this can be accomplished by surgery, but the propensity of cancers to invade adjacent tissue or to spread to distant sites by microscopic metastasis often limits its effectiveness. Chemotherapy is often limited by toxicity to other tissues in the body and radiation therapy can also cause damage to normal tissue.
The potentiation of innate anti tumour mechanisms by immunostimulatory compounds is a clinically relevant therapeutic approach to treating neoplastic disease. While NK and LAK cells play a central role in tumour cell surveillance and destruction, other innate immune cell subsets such as NKTs, monocytes/macrophages and dendritic cell subsets represent additional non-redundant arms of innate anti-tumour responses. Together these cell subsets are known to kill tumour targets by several mechanisms including granule-associated granzyme and perforin mediated killing as well as secretory mechanisms such as FasL, TRAIL and tumour necrosis factor-alpha (TNFα)-mediated pathways.
The potentiation of such cell subsets by an immunostimulant would provide an effective mono- or co-therapy for use in the treatment of neoplastic disease that is non-invasive and substantially less toxic than current treatment regimes.
Previously, applicant has disclosed an immunostimulant in the form of a muramyl dipeptide microparticle for the treatment of HIV and Anthrax in Australian Patent No. 732809 and New Zealand Patent Application No. 555582, respectively. However, Applicant has surprisingly and unexpectedly found that a muramyl dipeptide microparticle is useful in the treatment of neoplastic disease.
It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.